A document reading device mounts thereon an Automatic Document Feeder (ADF) used for automatically reading plural documents. The ADF includes a sheet feeding table for placing thereon a document before reading and a sheet discharging tray for placing a document after reading. When at least one document is placed on the sheet feeding table, the documents are sequentially fed toward a document reading position one by one from the uppermost document. Each of the documents is read at the document reading position by a scanner and is conveyed to the sheet discharging tray.
In such ADF, the sheet discharging tray is generally arranged under the sheet feeding table. As a result of that, a document after reading is discharged to a position hidden by the sheet feeding table. Therefore, a user may leave the document after the reading is completed. When the document is left, trouble such as loss of the document occurs. Also, leaving of the document has a problem in secrecy of a copying machine and the like used by plural users.
Hence, in order to prevent such a document from being left, JP-A-2001-312106 describes an image forming device for arranging a discharged document detecting sensor under a sheet discharging tray of the ADF. If it is detected that a document remains on the sheet discharging tray by the discharged document detecting sensor, this image forming device displays that the document remains, on a display panel at the front of the image forming device. By this display, attention to leaving of the document is drawn and the document is prevented from being left.
However, in the related-art image reading device as described above, it is necessary to add a dedicated sensor for detecting a document on the sheet discharging tray of the ADF. As a result, cost increases and a device configuration becomes more complex due to an increase in the number of components.